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Evidence-Based Series 21-2
A Quality Initiative of the
Brachytherapy for Cervical Cancer Expert Working Group (BCCEWG) Panel and the
Program in Evidence-Based Care (PEBC), Cancer Care Ontario (CCO)
The Delivery of Brachytherapy for Cervical Cancer: Organizational and
Technical Advice to Facilitate High-Quality Care in Ontario
Gerard Morton, Cindy Walker-Dilks, Fulvia Baldassarre,
David D’Souza, Conrad Falkson, and Deidre Batchelar
Report Date: November 11, 2009
An assessment conducted in November 2013 deferred the review of Evidence-based
Series (EBS) 21-2, which means that the document remains current until it is assessed
again next year.
EBS 21-2 is comprised of 4 sections
and is available on the CCO website (http://www.cancercare.on.ca)
PEBC Cancer Screening page at:
http://www.cancercare.on.ca/toolbox/qualityguidelines/clin-program/radther/
Section 1: Guideline Recommendations
Section2: Part A: Evidentiary Base
Section 2: Part B: Evidentiary Base: Secondary Question
Section 3: EBS Development Methods and External Review Process
For information about the PEBC and the most current version of all reports,
please visit the CCO website at http://www.cancercare.on.ca/ or contact the PEBC office at:
Phone: 905-527-4322 ext. 42822 Fax: 905-526-6775 E-mail: [email protected]
Journal Citation (Vancouver Style):
 Morton G, Walker-Dilks C, Baldassarre F, D'Souza D, Falkson C, Batchelar D, et al. Delivery of brachytherapy for
cervical cancer: organisational and technical advice to facilitate high-quality care. Clin Oncol (R Coll Radiol).
doi:10.1016/j.clon.2010.05.020. Epub 2010 Jun 25.
 D'Souza D, Baldassarre F, Morton G, Falkson C, Batchelar D. Imaging technologies for high dose rate brachytherapy
for cervical cancer: a systematic review. Clin Oncol. doi:10.1016/j.clon.2011.02.014. Epub 2011 Mar 25.
Guideline Citation (Vancouver Style): Morton G, Walker-Dilks C, Baldassarre F, D’Souza D, Falkson C, Batchelar D.
The delivery of brachytherapy for cervical cancer: organizational and technical advice to facilitate high-quality care
in Ontario. Toronto (ON): Cancer Care Ontario; 2009 Nov 11. Program in Evidence-based Care Evidence-based Series
No.: 21-2.
EBS 21-2
Evidence-Based Series #21-2: Section 1
The Delivery of Brachytherapy for Cervical Cancer:
Organizational and Technical Advice to Facilitate
High-Quality Care in Ontario:
Guideline Recommendations
Gerard Morton, Cindy Walker-Dilks, Fulvia Baldassarre,
David D’Souza, Conrad Falkson, and Deidre Batchelar
A Quality Initiative of the
Brachytherapy for Cervical Cancer Expert Working Group (BCCEWG) Panel and the
Program in Evidence-Based Care (PEBC), Cancer Care Ontario (CCO)
Report Date: November 11, 2009
QUESTIONS
What are the optimal organizational and technical requirements to ensure high-quality
and safe provision of high-dose-rate intracavitary brachytherapy (HDR BT) to treat cancer of
the cervix? The organizational domains of interest include:

Practice Setting: includes facility, equipment, delivery suite, imaging technologies,
treatment planning, and dosimetry.
Within the Practice Setting domain, the
Brachytherapy Cervical Cancer Expert Working Group (BCCEWG) Panel (see Section 2:
Part B, Appendix 1) identified a need for evidence to address the secondary clinical
question (see Section 2: Part B):
What is the utility of various imaging technologies (specifically,
fluoroscopy, ultrasound [US], computed tomography [CT], magnetic
resonance imaging [MRI], and positron emission tomography [PET])
that are used in brachytherapy (BT) for cervical cancer?
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Practice Team: includes team members, roles, training, team caseload/volumes, and
qualifications.
Quality Assurance: encompasses documentation, audit, safety, and quality control.
TARGET POPULATION
Women with cervical cancer of any stage treated with HDR BT.
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INTENDED USERS
The intended users of this guidance document are radiation oncologists, medical
physicists, dosimetrists, radiation therapists, gynecological oncologists, nurses,
administrators, and all care providers and planners involved in the delivery of BT for cervical
cancer
DEVELOPMENT OF RECOMMENDATIONS
Evidence on the organizational and technical issues concerning BT for cervical cancer
was gathered through an environmental scan and an iterative search of the literature to
locate guidance documents on the delivery of BT for cervical cancer. Ten documents that
were determined to be the most recent, comprehensive, and relevant to practice in Ontario
(1-10) provided a source for adapted recommendations.
The clinical effectiveness of HDR BT has been established in randomized clinical trials
(RCTs) (11), and HDR BT treatment is regarded as a standard of care for cervical cancer.
However, the choice of imaging technologies used in the delivery of BT is an important
clinical decision, and a separate systematic review of the literature on imaging technologies
for BT was conducted to inform recommendations for choosing one imaging modality over
another.
Although most of the organizational guidelines for BT that form the basis of the
present document are composed of narrative reviews and clinical expert opinion,
considerable consistency and an international consensus emerged among several guidelines
published worldwide on this topic. Furthermore, in areas such as caseload and team
composition, randomized trials would not be feasible, and the return on the investigation
might likely be limited. As well, the evidence that emerged from the systematic review of
studies on imaging technologies, although revealing a lack of definitive evidence, was
germane to the opinion of international experts published in the existing guidelines and to the
expert opinion of the members of the BCCEWG.
RECOMMENDATIONS
Domain 1 - Practice Setting/Physical Resources
Facility and/or delivery suite
 The facility needs to have a functional and safe procedure room for applicator placement.
 The same room, if adequately shielded, can be used for afterloading and treatment. It
should be equipped with appropriate radiation monitoring equipment, sensors, and
alarms.
 Imaging equipment should be provided in the procedure room or at least be readily
accessible, because images need to be taken repeatedly during the various phases of the
procedure. The following imaging modalities may be used at different phases of
treatment: traditional fluoroscopy or radiography, magnetic resonance imaging (MRI),
computed tomography (CT), ultrasound (US), and positron emission tomography (PET) (see
below for details).
 A designated area for treatment planning should be available for use during brachytherapy
sessions.
 Facilities should be available for storing, cleaning, and sterilising applicators.
 The facility should have a treatment control area where the team can, without being
exposed to radiation, visually monitor the patient during the procedure.
 A designated waiting room for outpatients should also be provided, adjacent to the
treatment room and containing lockable changing cubicles, toilet facilities, and a sitting
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area.
A designated ambulatory/recovery area with stretchers for patients who have had general
anesthetic or sedation is also required.
Required equipment
 A remote afterloading unit with a high-dose-rate source should be available.
 Commercial or custom applicators, appropriate for all clinical situations, compatible with
the imaging technologies used should be available. The applicators should be assembled,
reviewed for correct operation, and sent for appropriate sterilization.
 At least one full set of applicators per patient, and one additional set, should be
available.
 A sufficient number of connectors and dummy source trains should be provided.
 Standard safety equipment for radiation protection during fluoroscopy should be
available.
 General equipment for the care and monitoring of the patient during the procedure should
be available.
 A kit with supplies for dealing with a stuck- source emergency must be available inside the
treatment room.
 An operating room bed compatible with imaging (ideally a bed designed for
brachytherapy) should be available.
Imaging technologies
The BCCWG recommends:
 MRI for delineation of target volumes and planning. CT is acceptable for treatment
planning if MRI is not available, although CT provides inferior soft-tissue delineation and
cannot accurately delineate the target volumes.
 Ultrasound to guide the insertion of the uterine applicator.
Treatment planning
Treatment planning should be performed for each insertion and should involve the following:
 Acquisition of localization images: CT or MRI may be used to localize the applicators and
assess the anatomy. In some cases radiographs may be used to aid in the identification of
the applicators. CT or MRI should be used to evaluate the organs at risk (OAR) (CT/MRI)
and the target volume (MRI).
 Care must be taken to maintain the position of the applicators if the patient is moved for
imaging.
 Reconstruction of the applicators: A library of standard applicators may be used for fixed
geometry applicators. When flexible geometry applicators are used, the applicators must
be defined based on the localization images.
 Location of reference points: As a minimum, at least one prescription point and a point
for each critical organ must be defined. The most commonly accepted points are the
Manchester point A or equivalent for dose prescription and the bladder and rectal points,
based on the International Commission on Radiation Units and Measurement (ICRU) 38
definitions. With 3-dimensional (3D) imaging, volumes of interest should be defined for
the OAR (CT/MRI) and the target volume (MRI).
 Identification of source dwell positions: An institution may employ a library of standard
loading patterns for the dwell positions and times. When standard loading patterns are
used, doses to OAR should be assessed. Alternatively, individual plans may be created for
each patient. This individualization is generally aimed at limiting the dose to the OAR,
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based on the dose at standard points. When appropriate 3D imaging is available, dose
adaptation may be based on dose-volume histograms for the target and OARs. Dose
calculation is then performed using a specialized treatment planning system.
Dose adaptation should be carefully considered when target volumes are modified by the
use of CT or MR technology.
Independent verification and quality assurance of the plan is performed by another
member of the team or with another method.
Dosimetry
 The strength of the HDR BT sources should be specified by vendors in terms of air-kerma
strength. Upon receipt of the source, the medical physicist will confirm the source
strength using a well chamber with a calibration traceable to an interpolative secondary
standard. The institution’s calibration should agree with the vendor to within 3%.
Discrepancies greater than 3% should be investigated.
 Dose distributions are calculated by summing the contributions from each source position.
For each model of HDR BT source, the dose due to a single dwell position is determined
via Monte Carlo simulation techniques, other transport equation solutions, and
experimental dosimetry. This source data is published in peer-reviewed journals. The
medical physicist is responsible for verifying the accuracy of the source data in the
treatment planning system.
Domain 2 – Practice Team
Personnel
 The delivery of cervical BT requires the collaboration of a multidisciplinary team that
includes a radiation oncologist, medical physicist, dosimetrist, radiation therapist, nurse,
and radiation safety officer. The team may optionally include support from clerical staff,
gynecologic oncology, anesthesiology, medical imaging, and healthcare aides. BT is an
interdisciplinary procedure, and communication among team members is an essential
component of treatment. The roles described below are not mutually exclusive, but,
depending on case load and facility preferences, they may be performed by different
team members.
Roles and responsibilities
 The radiation oncologist is responsible for the overall medical care of the patient and for
the choice and placement of afterloading applicators, target volume, and normal tissue
identification and treatment prescription. The radiation oncologist must review and
approve the prescription and the treatment plan, attend the treatment, and remove the
applicators. Some of these duties may be delegated to appropriate staff, under
supervision.
 The medical physicist is responsible for the overall quality assurance of the treatment,
which includes commissioning of the treatment unit and applicators and reviewing the
quality assurance programme. The physicist supervises the planning process and confirms
the accuracy of the plan generated. If necessary, the physicist may also fulfil the role of
the dosimetrist. For each treatment, the physicist reviews the images and prescription
with the dosimetrist to develop a planning strategy, verifies the treatment plan and
calculations, checks the delivery time, checks the treatment unit program, and is
available in the immediate vicinity during treatment delivery. The physicist is responsible
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for the treatment planning and delivery; he or she should be able to problem solve during
planning and delivery. The medical physicist or delegate performs a survey of the patient
before and after each treatment.
The dosimetrist reviews the images and prescription, performs the treatment planning,
and delivers the plan parameters to the treatment unit.
The radiation therapist operates the BT treatment unit and performs a daily quality
assurance of the unit, acquires the images, sets up the patient, programs the unit, treats
the patient, checks for source retraction, completes the documentation, and secures the
unit.
The radiation safety officer needs to ensure that all Canadian Nuclear Safety Commission
(CNSC) regulations and license requirements are followed, including appropriate source
security.
The radiation therapist or nurse assists the radiation oncologist in the choice and
preparation of the applicator, patient set-up, and applicator insertion and removal.
The nurse should take the history of the patient, start intravenous lines, assist in the
sedation of the patient, administer medication, monitor the patient during the procedure,
deliver immediate post-treatment care to the patient, and perform any other delegated
medical act as the local situation requires. The nurse may also be responsible for the
cleaning of applicators and preparing them for sterilization.
The radiation safety officer and medical physicist are responsible for the radiation
protection of patients and personnel. This protection includes developing emergency
procedures for retrieving a stuck HDR BT source from the patient, as well as procedures
for checking the safety interlocks and the communications between the patient and the
operator; training professional and technical staff regarding HDR BT; and ensuring proper
functioning of in-room monitors, warning lights, and the portable survey instrument; and
ensuring that personnel monitoring is available for and used by all required staff.
Practitioner education and training
 Continuing education should target all personnel directly connected with administering
HDR BT. Programs must include the safe operation, including emergency procedures, of
HDR BT applicators and HDR BT remote afterloading equipment and sources, as
appropriate to the staff member’s responsibilities, and treatment techniques and new
developments in radiation oncology and brachytherapy. Radiation safety programs should
include any hospital-based personnel involved with brachytherapy patients. Radiation
oncologists, physicists, and associated brachytherapy personnel should be encouraged and
adequately resourced to attend multidisciplinary educational courses and meetings on BT
as part of their continuing professional development. Specific training on brachytherapy
dosimetry and source calibration should be made available to BT physicists.
 The radiation oncologist must possess the required technical skills for intrauterine
applicator placement, image interpretation, and understanding of dosimetry. It is
recognized that not all residency programs provide sufficient opportunity for the radiation
oncologist to acquire the necessary skills and further training (e.g., a fellowship,
Brachytherapy School) is desirable. The radiation oncologist’s training program should
include training in the nature of the applicators, observation of the placement of an
applicator, supervised placement of applicators, discussion of desired dose distributions,
instruction on the interpretation of the resulting information in order to devise a
treatment plan, instruction in the use of evaluation tools, and supervision during the
treatment of a patient.
 The radiation therapist training schedule should include programming and operating the
unit, daily quality assurance, and safety procedures, handling emergency procedures,
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monitoring the unit and patient during treatment, and detecting errors and potential
problems. It should include reviewing treatment planning system requirements for
localization and imaging and practice treatment delivery, and supervised operation during
a patient’s treatment.
The dosimetrist should have training in BT treatment planning and in the operation of the
specific treatment planning system.
The medical physicist training schedule should include programming and operating the
remote afterloading unit, acquiring full knowledge of overall quality assurance and safety
procedures, handling radiation emergency procedures, training as a dosimetrist in order to
participate in a patient’s treatment planning, evaluation of all information returned from
the planning system, practice in the use of the non-routine parts of the software, practice
in optimization in non-routine situations, recognizing that optimization has failed to
produce a desirable dose distribution and interventional techniques, and supervised
operation during a patient’s treatment. The physicist should also be trained in the
functioning of the afterloader, treatment console, imaging modalities (specifically x-ray
and US), applicators, and all associated accessories.
The nurse training schedule should cover BT specific issues.
The healthcare aide training should cover all instrument sterilization procedures, as well
as how to clean all the equipment present in BT room.
Team members must remain active (one procedure [BT of any site] per month) or take
refresher training.
All team members should have a basic understanding of aseptic techniques.
Qualifications:
 A radiation oncologist is a medical doctor with specialty certification in Radiation
Oncology from the Royal College of Physicians and Surgeons of Canada (RCPSC), or
equivalent certification.
 A qualified medical physicist is a physicist certified in Radiation Oncology Physics by the
Canadian College of Physicists in Medicine (CCPM) or holding equivalent certification.
 The dosimetrist should have the Dosimetry Specialty Certification (DSp), obtained through
the Canadian Association of Medical Radiation Technologists (CAMRT), or certification
through the American Medical Dosimetrist Certification Board (MDCB) as a Certified
Medical Dosimetrist (CMD) or equivalent certification.
 The radiation therapist will have completed an accredited educational program and be
certified by the CAMRT or equivalent, and be a member of the CMRTO.
 The nurse must be a registered nurse from the College of Nurses of Ontario (CNO).
Team Caseloads/Volumes
 An average of ten patients a year treated by each team with intracavitary BT insertions
for cervical cancer is the recommended minimum number to be performed to maintain a
service. Each physician should be involved in the cases treated by his or her team, or in
an equivalent number of cases to keep expertise up.
 BT should only be done at centres with direct access to appropriate gynecological
expertise for multidisciplinary patient assessment and treatment.
 It is estimated that four consecutive HDR BT procedures take four to eight hours of
medical physicist time, including treatment supervision and treatment plan review. One
full-time equivalent (FTE) of a qualified medical physicist should be allocated for an
average load of 10 cervix brachytherapy fractions per week, including quality assurance,
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staff training, and treatment record audits. Several back-to-back treatments in a single
day may require the participation of more than one treatment team (e.g., one to cover
applicator insertion and the other to perform treatment planning and delivery).
Domain 3 – Quality Assurance
Treatment Documentation
 Clear communication among all members of the HDR BT delivery team is critical. Such
communication is made possible by the use of unambiguous documentation fully
describing the treatment intent and delivery, including a prescription signed by the
radiation oncologist. Prior to the delivery of HDR BT for the cervix, written protocols and
procedures for the treatment should be developed and the duties of each team member
documented. Similarly, all quality assurance procedures should be written up formally,
and, to ensure compliance and completeness, check lists should be developed and used.
At a minimum, patient-specific documentation should include details allowing for the
quick assessment of treatment status and the reconstruction of treatments delivered in
the past. Institutions may decide to document further details, which may allow for the
detailed analysis of outcomes and facilitate inter-institutional comparisons.
Audit
 Audits and peer reviews of treatment plans are recommended to prevent and correct
errors and to ensure good practice. The goal of external audits is to provide an
independent check of the dose delivered to the patient. At the present time, large scale
auditing for BT is not available in Ontario. Should this become available in the future, the
BCCEWG suggests that centres in Ontario participate in this important safety procedure.
 Centre specific quality assurance protocols should be in place.
Safety
 The aim of all safety procedures is to minimize errors and prevent harm to the patients,
staff and visitors, and safety permeates all aspects of BT treatment procedures.
However, details of safety procedures are beyond the scope of this document, and the
BCCEWG invites interested readers to refer to the documents on this topic listed in
Section 2: Part A.
Quality Control
A quality control program needs to be performed by or under the supervision of a medical
physicist. Performance standards for the equipment for HDR BT should include:
 Functionality: Is the equipment working? How long may the present source be used to
keep treatment times reasonable?
 Reproducibility: Do the results of routine quality control measurements agree with those
taken during the commissioning of the unit?
 Accuracy: Does a measured value agree with its expected value?
 Characterization and documentation: Has the performance of all pieces of equipment
been fully characterized and documented?
 Data transfer and validation: Has the appropriate data been entered correctly and
transmitted accurately through all systems in use?
 Completeness: Have the quality control procedures and documentation been reviewed?
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The HDR afterloader undergoes daily, quarterly, and annual quality control checks. As long as
a measurement does not deviate from its expected value by more than the tolerance level, no
action is required. If a measurement deviates by more than the action level, remedial action
must be taken immediately. In addition to the afterloader, quality control checks to ensure
applicator and accessory functionality and integrity must be developed and performed
routinely.
RELATED GUIDELINES
 Program in Evidence-based Care Evidence-based Series #21-1 Organizational Standards for
the Delivery of Intensity Modulated Radiation Therapy (IMRT) in Ontario.
Funding
The PEBC is a provincial initiative of Cancer Care Ontario supported by the Ontario Ministry of Health
and Long-Term Care through Cancer Care Ontario. All work produced by the PEBC is editorially
independent from its funding source.
Copyright
This report is copyrighted by Cancer Care Ontario; the report and the illustrations herein may not be
reproduced without the express written permission of Cancer Care Ontario. Cancer Care Ontario
reserves the right at any time, and at its sole discretion, to change or revoke this authorization.
Disclaimer
Care has been taken in the preparation of the information contained in this report. Nonetheless, any
person seeking to apply or consult the report is expected to use independent medical judgment in the
context of individual clinical circumstances or seek out the supervision of a qualified clinician. Cancer
Care Ontario makes no representation or guarantees of any kind whatsoever regarding the report
content or use or application and disclaims any responsibility for its application or use in any way.
Contact Information
For further information about this report, please contact:
Dr. Gerard Morton, Dept. of Radiation Oncology, Sunnybrook Odette Cancer Centre, 2075 Bayview
Avenue, Toronto, ON, M4N 3M5, telephone (416)-4806165, e-mail: [email protected]
or
Dr. Padraig Warde, Provincial Head, Radiation Therapy Program, Cancer Care Ontario, 620 University
Avenue, Toronto, ON, M5G 2L7, telephone: (416) 971-9800 ext. 3734; Fax (416) 217-1281; e-mail
[email protected]
For information about the PEBC and the most current version of all reports,
please visit the CCO website at http://www.cancercare.on.ca/ or contact the PEBC office at:
Phone: 905-527-4322 ext. 42822 Fax: 905-526-6775 E-mail: [email protected]
RECOMMENDATIONS – page 8
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REFERENCES
1. American College of Radiology. ACR practice guideline for the performance of high-doserate brachytherapy [Internet]. Reston (VA); American College of Radiology; 2006 [revised
2005; cited 2008 Jun 27]. Available from:
http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/ro/high_do
se_rate_brachytherapy.aspx
2. American College of Radiology. ACR practice guideline for the performance of
brachytherapy physics: remotely loaded HDR sources [Internet]. Reston (VA); American
College of Radiology; 2006 [revised 2005; cited 2008 Jun 27]. Available from:
http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/med_phys/
brachy_remotely_loaded.aspx
3. Canadian Association of Provincial Cancer Agencies. Standards for quality control at
Canadian radiation treatment centres: brachytherapy remote afterloaders [Internet].
Toronto (ON): Canadian Association of Provincial Cancer Agencies; 2006 [cited 2008 Jul 2].
Available from:
http://www.medphys.ca/media.php?mid=125
4. International Atomic Energy Agency. Radiation protection in the design of radiotherapy
facilities [Internet]. Vienna: International Atomic Energy Agency; 2006 [cited 2008 Jul 2].
Safety Reports Series No.: 47. Available from:
http://www-pub.iaea.org/MTCD/publications/PDF/Pub1223_web.pdf
5. Kubo HD, Glasgow GP, Pethel TD, Thomadsen BR, Williamson JF. High dose-rate
brachytherapy treatment delivery: report of the AAPM Radiation Therapy Committee Task
Group No. 59. Med Phys. 1998 Apr;25(4):375-403.
6. Li Z, Das RK, DeWerd LA, Ibbott GS, Meigooni AS, Perez-Calatayud J, et al. Dosimetric
prerequisites for routine clinical use of photon emitting brachytherapy sources with
average energy higher than 50 kev. Med Phys. 2007 Jan;34(1):37-40.
7. Nag S, Dobelbower R, Glasgow G, Gustafson G, Syed N, Thomadsen B, et al. Inter-society
standards for the performance of brachytherapy: a joint report from ABS, ACMP and
ACRO. Crit Rev Oncol Hematol. 2003 Oct;48(1):1-17.
8. Potter R, Haie-Meder C, Van Limbergen E, Barillot I, De Brabandere M, Dimopoulos J,
et al. Recommendations from gynaecological (GYN) GEC ESTRO working group (II):
concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy3D dose volume parameters and aspects of 3D image-based anatomy, radiation physics,
radiobiology. Radiother Oncol. 2006 Jan;78(1):67-77.
9. The Royal College of Radiologists. The role and development of brachytherapy services in
the United Kingdom [Internet]. London: The Royal College of Radiologists; 2007 [cited:
2008 Jun 27]. Available from:
http://www.rcr.ac.uk/docs/oncology/pdf/Brachytherapy_web.pdf
10. Venselaar J, Pérez-Calatayud J. A practical guide to quality control of brachytherapy
equipment [Internet]. Brussels (Belgium): European Society for Therapeutic Radiology and
Oncology (ESTRO); 2004 [cited 2008 Jun 30]. Booklet No.: 8. Available from:
http://www.estro-education.org/publications/Documents/booklet8_Physics.pdf
11. National Institute for Clinical Excellence. High dose rate brachytherapy for carcinoma of
the cervix – guidance [Internet]. London: National Institute for Clinical Excellence (NICE);
2006 Mar 22 [cited 2008 Jun 30]. Interventional Prevention Guidance No.: 160. Available
from: http://www.nice.org.uk/guidance/IPG160
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